Rotor blade assembly



June 2, 1970 J'. PALFREYMAN ETAL ,5 5,

- ROTOR BLADE ASSEMBLY Filed April 11, 1968 SSheets-Shet 1' Inventors A Home 3,15

June 2, 1970 J. PALFREYMAN ETAL ,5 0

ROTQR BLADE ASSEMBLY Filed April 11, 1968 l 3 Sheets-Sheet 2 Inveniors (,ZV/ WWI/MAW WWW W Aurneys 5mm 2, 1970 J. PALF'REYMAN ETAL 3,515,501

ROTOR BLADE ASSEMBLY 3 Sheets-Sheet 5 Filed April 13., 3.968

Inventors AHorneyQ- United States Patent ()ffice 3,515,501 Patented June 2, 1970 3,515,501 ROTOR BLADE ASSEMBLY Jack Palfreyman, Tansley, near Matlock, Derby, and Henry Edward Middleton, Derby, England, assignors to Rolls-Royce Limited, Derby, England, a British company Filed Apr. 11, 1968, Ser. No. 720,600 Claims priority, application Great Britain, Apr. 12, 1967, 16,873/ 67 Int. Cl. F01d /24 US. Cl. 416-193 11 Claims ABSTRACT OF THE DISCLOSURE The invention concerns a method of making a rotor blade assembly comprising forming at least one row of angularly spaced apart blades, and interconnecting the root portions of the blades by means of at least one length of fibrous material through which are transmitted centrifugal stresses produced on rotation of the assembly.

This invention concerns a method of making a rotor blade assembly, for example a bladed rotor of a gas turbine engine.

According to the present invention, there is provided a method of making a rotor blade assembly comprising forming at least one row of radially extending, fiber reinforced, angularly spaced apart rotor blades, each of said rotor blades having a root portion with at least one recess defined in the outer surfaces thereof, said recesses in said plurality of blades forming a continuous recess around the periphery of said blade assembly, winding a plurality of turns of the fibrous material circumferentially of said blade assembly in said recesses in a manner as to interconnect said root portions and in a manner such that centrifugal stresses produced on rotation of said blade assembly will be transmitted through said turns of said fibrous material and bonding said turns of said fibrous materials in said recesses.

As will be appreciated, the turns of fibrous material in addition to enabling the blade assembly to withstand centrifual stresses produced on rotation thereof, interconnect the blades by means of a construction which may be both stronger and lighter than that hitherto used.

The root portion of each blade is preferably provided with two recesses which are respectively disposed on opposite sides of the blade profile.

After the said blades have been wound in the said recesses, they may be compacted therein.

The fibrous material preferably comprises carboniferous or boron fibers.

The fibers of the fibrous material may be coated with a synthetic resin material such, for example, as an epoxy, polyimide, polyquinoxaline or polythiazole resin.

Alternatively, the fibers may be coated with a metal or alloy. Thus, the metal may be beryllium, cobalt, chromium, nickel, hafnium, niobium, osmium, paladium, platiniurn, rhenium, rhodium, tantalum or vanadium, while the said alloy may be a nickel-chromium alloy.

The fibers may be coated by passing them through a bath of the said metal or alloy. Thus the fibers may be coated by being electrolytically plated with the said metal or alloy. Alternatively, the fibers may be coated by spraying or vacuum depositing the metal or alloy.

Carboniferous textile fibers may, for example, be passed through an oven and thence directly to the said bath.

The fibers, after passing through the said bath, may be wound directly about the said root portion.

The fibers which have been wound about the said root portions may thereafter be bonded thereto. Thus, in the case of fibers which have been coated with a metal or plating, brazing, electron beam Welding, or spraying with a metal or alloy.

The said blades may, if desired, be fiber-reinforced.

The invention also comprises a blade assembly when made by the method set forth above. Moreover, the invention also comprises a gas turbine engine provided with such a blade assembly. Thus, the said gas turbine engine may have a blade assembly comprising a rotor drum which is provided externally with at least one row of fan blades and which is provided internally with a plurality of rows of rotatable guide blades of a compressor of the engine, the root portions of the said rows of rotatable guide blades being secured to the rotor drum by the said fibrous material.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which:

FIG. 1 is a diagrammatic view illustrating the method of the present invention of making a blade assembly,

FIG. 2 is a broken-away respective view of a part of the blade assembly made by the method illustrated in FIG. 1, and

FIG. 3 is a diagrammatic view, partly in section, of a gas turbine front fan engine having a blade assembly made by the said method.

Referring first to FIG. 1, a plurality of angularly spaced apart radially extending rotor blades 10 are held in juxtaposition by means of a jig (not shown) to form a rotor blade assembly comprising in this case a single row of blades.

As best shown in FIG. 2, each of the blades 10 has a root portion 12 having a curved radially inner surface 13 which forms a continuous cylindrical surface when the blades 10 are assembled. Each of the root portions 12 is provided on opposite sides of its blade profile 14 with two recesses 15, 16 which extend to radially outer surfaces 17, 18 of the root portions 12.

The recesses 15 of the row of blades 10 are aligned with each other so as to form portions of, in effect, a single circumferentially extending recesses when the blades 10 are assembled, and which also extends about the root portions 12 of all the blades of the said row of blades. The recesses 16 are similarly aligned with each other.

Carboniferous textile fibers 21, e.g. as suggested in our copending British patent applications Nos. 14,476/ 65 and 49,850/ 65, are passed through an oven 22 and are thence passed directly to an electrolytic plating bath 23 where the fibers are plated electrolytically with a metal or alloy, e.g. an nickel-20% chromium alloy.

The fibers 21, after passing through the bath 23, are

' then Wound directly about the root portions 12 of the row of blades 10 by winding a large number of turns of the coated fibers 21 in each of the recesses 15, 16, egg. by rotating the blade assembly about its axis of rotation. In this way the root portions 12 are interconnected, the

, fibers 21 being adapted to withstand centrifugal forces to which the rotor blades 10 are subjected in operation. As will be appreciated,each turn of the coated fibers 21, will then extend circumferentially of the blade assembly,

and will extend about the root portions 12 of all the in the recesses 15, 16 are thereafter bonded therein. This may be done before the jig is removed by placing the jig with its blades 10 in an electrolytic plating bath and bonding the coated fibers 21 to the root portions 12 by the plating material, the jig having been coatedwith an insulating material which will prevent the jig itself being plated. Alternatively, the bonding may be effected by brazing, explosion welding, electron beam welding, laser welding, diffusion welding, or hot pressing. When this has been done, the jig is removed.

During or after assembly the blades may be secured to a rotor disc or drum (not shown) of conventional type, for example by bonding. Alternatively spacer members (not shown) may be secured to the sides of the root portions 12 to form an integral rotor structure.

The blades 10 may be formed of conventional mate rials. Alternatively they may be made of coated fibers which may, for axample, be the same as the coated fibers 21.

The carboniferous fibers referred to above may be replaced by boron or other fibers, while the nickel-chromium alloy coating on the fibers 21 may be replaced by a coating of beryllium, cobalt, chromium, nickel, haf nium, niobium, osmium, paladium, platinum, rhenium, rhodium, tantalum or vanadium. The coating metal is chosen having regard to its mechanical properties at the temperature at which the bladed rotor is to operate.

Moreover, the fibers 21, instead of being coated with a metal or alloy, may be coated with a synthetic resin material such as an epoxy, polyimide, polyquinoxaline, or polythiazole resin. In this case, however, after the fibers 21 have been wound into the recesses 15, 16 they are resin bonded therein by injecting further synthetic resin material.

If desired, the rotor blade assembly may comprise a plurality of rows of blades 10, some of the fibers 21 being arranged to extend over and to be drivingly connected to the portions of the outer surfaces 17, 18 of the root portions 12 between the adjacent recesses 15, 16.

The rotor blade assembly illustrated in FIGS. 1 and 2 is particularly suitable for use in the rotor of a compressor of a gas turbine engine, although it may also be used in the construction of the turbine thereof.

In FIG. 3, there is illustrated, diagrammatically, one particular gas turbine engine, part of which may be made by the method illustrated in FIGS. 1 and 2.

In FIG. 3 there is shown a gas turbine engine 24 which is provided with an engine casing 25 within which there are arranged in flow series, intake struts 26, a compressor 27, outlet guide vanes 28, combustion equipment 29, nozzle guide vanes 30, and a turbine 31.

The compressor 27 has three axially spaced rows of rotor blades 34, which are driven by the turbine 31 by way of a shaft 35. The compressor 27 is also provided with four axially spaced rows of rotatable guide blades 36 which form, in eifect, stators of the compressor 27. The rows of blades 36 are provided internally of a rotor drum 40, the drum 40 being provided externally with a row of fan blades 41 of a front fan 42. The blades 41 are mounted within a fan duct 43 which is defined between the rotor drum 40 and an outer casing 44, the latter being supported from the casing 25 by way of front and rear struts 45, 46 respectively.

The air passing through and being compressed by the rotor blades 34 of the compressor 27 is arranged to drive the rotatable guide blades 36 which thus in turn drive the fan blades 41.

The rotatable guide blades 36 are of the form illustrated in FIGS. 1 and 2 and are interconnected by the fibers 21.

We claim:

1. A method of making a rotor blade assembly comprising forming at least one row of radially extending, fiber reinforced, angularly spaced apart rotor blades, each.

of said rotor blades having a root portion with at least one recess defined in the outer surface thereof, said recesses in said plurality of blades forming a continuous recess around the periphery of said blade assembly,

winding a plurality of turns of a fibrous material circumferentially of said blade assembly in said recesses in a manner as to interconnect said root portions and in a manner such that centrifugal stresses produced on rotation of said blade assembly will be transmitted through said turns of fibrous material and bonding said turns of said fibrous materials in said recesses.

2. A rotor blade assembly comprising at least one row of radially extending, fiber reinforced, angularly spaced apart rotor blades, each of said rotor blades having a root portion with at least one recess defined in the outer surface thereof, said recesses in said plurality of blades forming a continuous recess around the periphery of said blade assembly, and

a plurality of turns of a fibrous material wound circumferentially of said blade assembly in said recesses and bonded in said recesses in a manner as to interconnect said root portions and in a manner such that centrifugal stresses produced on rotation of said blade assembly will be transmitted through said turns of fibrous material.

3. A blade assembly comprising a rotor drum having mounted externally thereon at least one row of fan blades and having mounted internally thereon a plurality of rows of rotatable guide blades of a gas turbine engine compressor,

each of said rotatable guide blades having a root portion with at least one recess defined in the outer surface thereof such that said recesses in the rotatable guide blades forming each of said rows forms a continuous recess around the periphery of each of said rows,

a plurality of turns of a fibrous material wound circumferentially of each of said rows in said recesses and bonded therein in a manner as to connect said root portions in each of said rows and in a manner such that centrifugal stresses produced on rotation of said rotor drum will be transmitted through said turns of said fibrous material, said root portion of said rows of rotatable guide blades being secured to the rotor drum by said fibrous material.

4. A method as claimed in claim 1 in which the root portion of each blade is provided with two of said recesses which are respectively disposed on opposite sides of the blade profile.

5. A method as claimed in claim 4 in which, after the said turns have been'wound in the said recesses, they are compacted therein.

6. A method as claimed in claim 1 comprising the additional step of coating the fibers of the fibrous material with a synthetic resin material.

7. A method as claimed in claim 1 comprising the additional step of coating the fibers with a metal or alloy.

8. A method as claimed in claim 7 in which said coating step comprises passing the fibers through a bath of said metal or alloy.

9. A method as claimed in claim 8 in which the fibers are coated by being electrolytically plated with the said metal or alloy.

10. A method as claimed in claim 8 comprising the additional step of passing carboniferous textile fibers through an oven and thence directly to said bath.

11. A method as claimed in claim 8 in which the fibers, after passing through the said bath, are passed directly to the said root portions.

References Cited UNITED STATES PATENTS (Other references on following page) 5 References Cited 6 FOREIGN PATENTS 611,006 12/1960 Canada.

EVERETTE A. POWELL, JR., Primary Examiner Secord et a1.

Erwin.

Neumann 25377.2 Martin et a1.

Banger et a1.

Blackhurst et a1.

US. C1. X.R. 

